Ultrafiltration membranes and methods of making and use of ultrafiltration membranes

Patent metadata

Field	Value
Publication number	US-9415353-B2
Application number	US-65898010-A
Country	US
Kind code	B2
Filing date	Feb 18, 2010
Priority date	Oct 14, 2005
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

An inherently hydrophobic polymer membrane substrate having its surface rendered hydrophilic with a hydroxyalkyl cellulose and having a throughput greater than about 1500 L/m 2 is provided. A process for making the membrane also is provided which includes a step of autoclaving in boiling water and/or steam or submerging in boiling water. The membrane is useful for removing virus from a protein solution.

First claim

What we claim:

1. A process for forming a virus-retentive ultrafiltration membrane having an improved flux, the process comprising the steps of:
(a) providing a multilayer substrate membrane comprising at least one microporous layer and an ultrafiltration layer;
(b) contacting the substrate membrane with a solution of hydroxypropyl cellulose to adsorb said hydroxypropyl cellulose onto the substrate membrane;
(c) removing excess hydroxypropyl cellulose from the substrate membrane by rinsing in water; and
(d) subjecting the rinsed substrate membrane to a step selected from the group consisting of: (1) autoclaving in the presence of steam or water; and (2) submerging in boiling water, thereby to form a virus-retentive ultrafiltration membrane having an improved flux relative to a membrane not subjected to step (d) subsequent to optionally rinsing in water, and further wherein the membrane has log reduction value (LRV) for Phi X174 of at least 4.0 and a throughput of 1000 L/m 2 .

2. The process of claim 1 , wherein step (d) comprises submerging the membrane substrate in boiling water.

3. The process of claim 1 , wherein step (d) comprises autoclaving the membrane substrate in the presence of steam or water.

4. A process for forming a virus-retentive ultrafiltration membrane having an improved flux, the process comprising the steps of:
(a) providing a membrane having at least one microporous layer formed from a first sulfone polymer and an ultrafiltration layer formed from a second sulfone polymer;
(b) contacting the membrane with a solution of hydroxyalkyl cellulose to adsorb the hydroxyalkyl cellulose onto the membrane;
(c) removing the excess hydroxyalkyl cellulose by rinsing the membrane in water; and
(d) subjecting the rinsed membrane to a step selected from the group consisting of: (1) autoclaving in the presence of water or steam; and (2) submerging in boiling water, thereby to form a virus-retentive ultrafiltration membrane having an improved flux relative to a membrane not subjected to step (d) subsequent to optionally rinsing in water, and further wherein the membrane has log reduction value (LRV) of at least 4.0 for Phi X174 and a throughput of at least 1000 L/m 2 .

5. The process of claim 4 , wherein the hydroxyalkyl cellulose is hydroxylpropyl cellulose.

6. The process of claim 4 , wherein the first sulfone polymer and the second sulfone polymer are the same sulfone polymer.

7. The process of claim 6 , wherein the same sulfone polymer is polysulfone.

8. The process of claim 6 , wherein the same sulfone polymer is polyethersulfone.

9. The process of claim 4 , wherein either the first sulfone polymer or the second sulfone polymer is polysulfone.

10. The process of claim 4 , wherein either the first sulfone polymer or the second sulfone polymer is polyethersulfone.

11. The process of claim 1 , wherein the flux is improved relative to a membrane not subjected to step (d) subsequent to rinsing in water.

12. The process of claim 4 , wherein the flux is improved relative to a membrane not subjected to step (d) subsequent to rinsing in water.

13. The process of claim 1 , wherein the resulting membrane comprises a higher critical wetting surface tension and/or a higher throughput relative to a membrane not subjected to step (d) subsequent to rinsing in water.

14. The process of claim 4 , wherein the resulting membrane comprises a higher throughput relative to a membrane not subjected to step (d) subsequent to rinsing in water.

15. The process of claim 4 , wherein solution of hydroxyalkyl cellulose comprises 10-30% alkanol.

16. The process of claim 15 , wherein the alkanol is isopropyl alcohol.

17. The process of claim 15 , wherein the hydroxyalkyl cellulose is hydroxypropyl cellulose and the solution comprises from about 0.5 to about 1.0% hydroxypropyl cellulose.

18. The process of claim 4 , wherein the membrane has a throughput of at least 1500 L/m 2 .

19. The process of claim 4 , wherein the membrane is formed by a cocasting process of first and second sulfone polymers.

20. The process of claim 4 , wherein the membrane is contacted with the solution of hydroxyalkyl cellulose for about 2 to about 60 minutes.

21. A process for forming a virus-retentive ultrafiltration membrane having an improved flux, the process comprising the steps of:
(a) providing a membrane comprising at least one microporous layer formed from a first sulfone polymer and an ultrafiltration layer formed from a second sulfone polymer, wherein the membrane is formed by a cocasting process of the first and second sulfone polymers;
(b) contacting the membrane with a solution of hydroxyalkyl cellulose comprising 10-30% alkanol for about 2 to about 60 minutes to adsorb the hydroxyalkyl cellulose onto the membrane;
(c) removing the excess hydroxyalkyl cellulose by rinsing the membrane in water; and
(d) subjecting the optionally rinsed membrane to a step selected from the group consisting of:
(1) autoclaving in the presence of water or steam; and (2) submerging in boiling water, thereby to form a virus-retentive ultrafiltration membrane having an improved flux, and further wherein the membrane has log reduction value (LRV) of at least 4.0 for Phi X174 and a throughput of at least 1500 L/m 2 , wherein throughput is the maximum volume of 1.45 g/L Bovine Serum Albumin (BSA) solution in 150 mM NaCl, pH 7.2, that can be filtered at 30 pounds per square inch (psi) constant pressure at 22° C. through one square meter of the membrane before less than 10% of the original flux of the membrane is observed when effecting filtration with the membrane to attain virus retention of an LRV of 3.5 or greater.

Assignees

• Moya Wilson
• Kozlov Mikhail
• Emd Millipore Corp

Inventors

• Moya Wilson
• Kozlov Mikhail

Classifications

• A61L2/022

  Filtration · CPC title

• A61L2103/05

  Living organisms or biological materials · CPC title

• B01D71/68 Primary

  Polysulfones; Polyethersulfones · CPC title

• B01D67/0088

  Physical treatment with compounds, e.g. swelling, coating or impregnation · CPC title

• B01D67/0083

  Thermal after-treatment · CPC title